The invention relates to an anti-theft device for bicycles, which comprise a bicycle frame and a steering column mounted on the bicycle frame for steering the bicycle, which steering column is provided for a rotationally fixed coupling of a bicycle handlebar with a fork for a front wheel, having a separating means for neutralising the rotationally fixed coupling.
Such anti-theft devices are known. Unlike a conventional U lock, for instance, which in a secured position is disposed in an exposed position on the bicycle and for this reason provides a thief with contact points for possibly forced opening, the above-mentioned anti-theft device enables improved protection of the bicycle against theft, since the thief, even if he is prepared to use force, cannot neutralise the action of the anti-theft device without damaging the bicycle.
In the case of a U-type lock, a classic security principle comes to be used, which consists in bringing parts which are constructed on the article to be secure and move in relation to one another into a more or less fixed or stationary position with respect to one another so that the movability of the parts is limited and the item cannot be used in the secured position. Provided that the item to be secured is a bicycle, as is known free rotatability of the rear wheel, for instance, is prevented by the U-type lock being placed both around a tube of the bicycle frame and also around a portion of the rim of the rear wheel and then being locked.
Alternatively, the U-type lock can also be positioned around the tube of the bicycle frame and around a fixed object, such as, for instance, a lamp post, so as to prevent the movability of the bicycle overall.
WO 92/10392 discloses a handlebar locking device for bicycles. The device comprises a locking mechanism in a handlebar front part, which brings the handlebar front part either in a non-secured position to engage with the front wheel fork or in the secured position separates it from said fork so that the steering column and the front wheel forks are freely rotatable with respect to one another. A steering column fixed to the front wheel fork and a tubular piece fixed to the handlebar front part are connected to one another in rotationally fixed manner in the non-secured position and can rotate together in a bicycle frame section. A cam actuated by means of a key moves a roller lock disposed in the steering column radially outwards and for releasing the safety device introduces it into a socket situated in the tubular piece so that the bicycle can be controlled. The cam also enables the introduction of the roller lock into an opening which is provided to separate the front wheel fork from the handlebar fore part, so that the bicycle cannot be steered and as a result is protected against theft. The known anti-theft device thus works in reverse to the safety principle described above in that to be precise a secure connection of two parts which is required for the operation of the bicycle is removed in the secured position.
The known anti-theft device offers no practical opportunity for producing a release of the lock by the application of force. The known anti-theft device is nevertheless disadvantageous inasmuch as a skilled thief may neutralise it to release the security device of the bicycle without causing any damage. This is of course a problem with respect to the protection of valuable bicycles, which are naturally of interest to a thief and with which, to obtain their resale value, an application of brute force is out of the question for the conscientious thief, so that the thief is prepared to study and learn the unauthorised nuetralisation of the anti-theft device in detail.
The object of the invention is to create an anti-theft device for bicycles, the release of which poses a thief a considerably more difficult task than known anti-theft devices.
This object is achieved with the device of the type mentioned at the beginning in that a coupling piece or a connecting element is provided as a separating means, which divides the steering column into two parts and which produces the rotationally fixed coupling of these steering column parts in a first state and neutralises it in the second state.
With the invention one obtains an anti-theft device which is clearly more difficult to release than known anti-theft devices when the coupling piece or the connecting element is removed by a user from the bicycle in a secured position. The anti-theft device according to the invention is highly integrated into the bicycle.
The coupling piece or the connecting element has an essentially reflection-symmetrical or point-symmetrical design. On either side of the plane of symmetry it has recesses and/or projections, which in the first state are in engagement with complementary means constructed on the steering column parts and at the same time produce a form-fit and/or frictional connection and in the second state are released from the complementary means.
In a first embodiment of the invention, the coupling piece is constructed with a column piece, which in the first state is inserted between the parts of the steering column and aligns with them and which in the second state is completely removed from the parts of the steering column. In the first state the bicycle is not secured. The column piece inserted between the parts of the steering column enables a rotationally fixed connection of the parts of the steering column with one another, so that the steering column with the coupling piece according to the invention is in practice not restricted in its function in comparison with a conventional steering column. The bicycle is secured in the second state. The parts of the steering column are disposed with coaxial spacing in relation to one another. The coupling piece, which is completely removed in the second state, is required to produce a connection of the parts of the steering column and thus the operability of the steering column again. Provided that a correct coupling piece is not inserted between the parts of the steering column, the use of the bicycle is prevented and is therefore of no interest to a thief.
Furthermore, the coupling piece comprises two coupling sleeves disposed axially next to one another. The column piece is housed in the coupling sleeves. The coupling sleeves comprise external threads, which are provided for an engagement with an internal thread in the respective adjacent portion of the bicycle frame. In the secured position the coupling sleeves are axially adjacent; in the non-secured position they are spaced from one another. Upon the transition from the secured position into the non-secured position, the coupling sleeves are screwed into the respective adjacent portion of the bicycle frame. Provided that the coupling sleeves have threads running in the same direction, the directions of rotation of the coupling sleeves are opposite during screwing in and unscrewing. It is advantageous if the coupling sleeves have threads running in opposite directions to one another, because then the directions of rotation of the two coupling sleeves agree when screwing in and unscrewing. The column piece can preferably be twisted coaxially in the coupling sleeves around its longitudinal axis and is also disposed to be axially displaceable.
In a preferred embodiment, the external threads on the coupling sleeves and the associated internal threads in the respective adjacent portion of the bicycle frame are individually matched to one another. As a result of the individual matching of the threads to be made to mesh with one another, only the external threads situated on the associated coupling pieces can be screwed into the respective adjacent portion of the bicycle frame. A different coupling piece to that individually provided in contrast has coupling sleeves whose external threads cannot be brought into engagement with the internal thread of the respective adjacent portion of the bicycle frame. With this individualisation of the coupling piece with respect to the particular bicycle frame, a particularly high degree of protection against theft is achieved.
The threads are preferably multiple-start, so that upon a rotation of the coupling sleeves a relatively large axial movement of the coupling sleeves is possible. Just one revolution of the coupling sleeves around the column piece is particularly preferably sufficient to achieve an axial movement by a predetermined insertion length of the respective coupling sleeve. With this preferred embodiment, a simple rotation of the coupling sleeves is sufficient to secure and release the safety device of the bicycle.
The column piece and the coupling sleeves are housed in a protecting tube. The protecting tube can be detached from the bicycle frame and comprises axially displaceable carriers. The carriers entrain the coupling sleeves upon a rotation of the protecting sleeve in relation to the bicycle frame. The carriers are preferably constructed as radial pins, which protrude outwardly through at least one axial slot in the protecting tube and of which one of the pins is engaged with one of the coupling sleeves. The protecting tube protects the user from dirt, which occurs, for instance, by lubricants from the connection between coupling sleeves and column pieces. The protecting tube also protects the column piece and the coupling sleeves from the entry of impurities and moisture, by which effective protection against corrosion in particular is achieved. If the device is in the non-secured position, the protecting tube also protects the adjacent portions of the bicycle frame from the entry of impurities and moisture. For the user the protecting tube reduces the danger of injury, since it preferably closes smoothly with the bicycle frame, so that the operation of the anti-theft device is particularly simple. Because the protecting tube is inserted into the bicycle frame, the anti-theft device according to the invention is disposed in a particularly inconspicuous manner in the bicycle. Alternatively, the protecting tube can be made conspicuous in order to display the anti-theft device on the bicycle and to represent it to the user as a desirable product.
In a second embodiment of the invention, the connecting element has an annular or frame-shaped construction. It comprises engagement bars which are provided for an engagement with claws of the steering column parts in the first state. Each engagement bar is grasped by the claw of the associated steering column part in the first state, the non-secured position. The engagement bars move from the first state into the second state by a first rotational movement of the connecting element around its centre axis at preferably right angles to the axis of the steering column. In the second state, the secured position, the connecting element is lodged freely between the steering column parts. The connecting element can be transferred from the second state, the secured position, into the first state, the non-secured position, by a second rotational movement in the opposite direction to the first.
In the second state, through an opening in the wall of the bicycle frame portion with the steering column, the connecting element can be removed from it and inserted into it. The safety device is particularly effective when the connecting element is completely removed from the steering column. For the thief it is a very difficult task to produce the connection between the steering column parts if the correct connecting element is not available to him.
On a section of the engagement bars facing the centre axis, the connecting element preferably comprises an individual profile or fitting profile, which can be brought into engagement with a complementary profile or fitting profile on the claws. Because of the complementary profile on the claws, the construction of the individual profile on the associated portion of the connecting element is necessary for releasing the anti-theft device specified by the invention. Thus unauthorised release of the safety device is made even more difficult.
According to one embodiment of the invention, the engagement bars of the connecting element are separated from one another possibly in the plane of symmetry and are disposed with radial displaceability with respect to the centre axis. The engagement bars can be brought into engagement with locking recesses in the steering column parts.
The axial sections of the locking bars can be brought into engagement with recesses in the end sides of the steering column parts. If in the non-secured position the expansion frame halves are in each case brought to engage in the end sides of the steering column parts, it is guaranteed that an uncontrolled backward rotation out of the non-secured position, in which the steering column parts are connected to one another in rotationally fixed manner, into the secured position, in which steering column parts are separated from one another and are freely rotatable with respect to one another, is prevented. Thus the operational safety of the bicycle is guaranteed when the anti-theft device is situated in the non-secured position.
In a further development according to the invention of the connecting element, the engagement bars form an inner ring which is surrounded by an outer ring. The outer ring comprises locking bars which are separated from one another with the formation of end faces preferably in the plane of symmetry of the connecting element. The locking bars are in each case displaceably mounted on the associated engagement bar of the inner ring. The locking bars are initially stressed with respect to one another. The outer ring also comprises one or more expansion elements for pushing apart the locking bars against the initial stress. The expansion elements are in each case rotatably mounted around the centre axis between the end faces of the locking bars. By rotating the expansion elements, the locking bars can be pushed apart. In this embodiment of the invention, the operational safety is particularly high because in the non-secured position the connecting element is grasped in frictional and/or form-fit manner both by the claws and also in the corresponding recesses in the steering column parts when the locking bars are pushed apart.
In a plane through which the centre axis passes at right angles, the cross-sectional profile of the expansion element is substantially rectangular with two wide and two narrow sides, which in each case lie opposite one another. If, in the secured position, the connecting element is inserted between the steering column parts, the expansion elements are disposed between the locking bars of the outer ring in such a manner that they press with the end faces of their free ends against the wide side faces of the expansion element. The oppositely disposed end faces of the locking bars have a distance between them which essentially corresponds to the narrow side of the rectangular cross-sectional profile of the expansion element.
If the connecting element is introduced between steering column parts and the expansion elements are rotated, the locking bars and the engagement bars follow a first quarter-circle rotation of the expansion elements. The engagement bars are grasped by the claws. The connecting element cannot follow a second quarter-circle rotation of the expansion elements around the centre axis, as the engagement bars are grasped by the claws. Therefore the second quarter-circle rotation results in the expansion element between the end faces of the locking bars being rotated by 90xc3x8. The locking bars are pushed apart or wedged apart by the expansion element according to the difference in length between the wide side and narrow side of the cross-sectional profile of the expansion element. Upon the second quarter-circle rotation of the expansion elements, the outer ring of the connecting element is thus expanded. An unintentional twisting of the expansion element is avoided by the fact that in the course of the quarter-circle rotation the locking bars have to be pushed apart against the initial stress at first up to a maximum, more precisely over the length of the diagonals of the rectangular cross-sectional profile.
The cross-sectional profile of the expansion element preferably comprises rounded corners so that the rotatability of the expansion element between the end faces of the initially stressed locking bars is increased.
The sides of the cross-sectional profile of the expansion element preferably have a concave design. The cross-sectional profile of the locking bar in the portion of the free ends preferably has a convex design so that the locking bar fits with the convex end face against the concave side face of the expansion element. With this design of the outer ring, the danger of an unintentional twisting of the expansion elements is particularly low. Thus the operational reliability of the bicycle in the non-secured position of the anti-theft device according to the invention is particularly high.
The anti-theft device according to the invention which is described above is situated in a bicycle having a bicycle frame and a steering column for steering the bicycle which is mounted on the bicycle frame and which is provided for a rotationally fixed coupling of a bicycle handlebar with a fork for a front wheel. Although the anti-theft device according to the invention which is described above is particularly suitable for protecting bicycles from theft, the person skilled in the art may easily deduce further areas of application, such as the protection of motor-driven two-wheelers or other vehicles having a steering column.